Joint dislocations in the human body are an increasingly common occurrence. Many of these dislocations involve varying degrees of associated ligament damage. Often, in minor injuries, the ligaments are able to heal with rest and external immobilization. However, more severe or chronic injuries to the joint require surgical intervention and internal stabilization or “casting” of the bone forming the joint to allow for proper healing. Common joint dislocations of this type include the acromioclavicular joint of the shoulder, which involves: (1) the acromioclavicular (AC) ligaments that join the clavicle and the acromium of the scapula; and (2) the coracoclavicular (CC) ligaments that join the coracoid bone to the clavicle. Other syndesmotic joints such as the distal tibiofibular joints are often similarly dislocated with associated ligament damage. In the case of the AC joint injury, commonly known as “separated shoulder”, AC ligaments and the CC ligaments are injured, causing upward displacement of the clavicle bone relative to both the acromium and coracoid bones. Surgical stabilization of such an injured joint involves the reduction of the clavicle relative to these bones, typically via some sort of mechanism designed to pull the clavicle down into proper alignment and hold it there while healing occurs.
Surgical techniques have been developed to accomplish this stabilization and numerous mechanisms have been devised. For an open surgical approach, sutures or other band-like devices are placed around the coracoid and attached over the clavicle. Often a tendon graft is utilized in this manner to provide a biological proxy to the injured ligaments. However, there is an ever-increasing demand for more minimally invasive surgical techniques. Minimally invasive or arthroscopic techniques have been developed and mechanisms devised (e.g., Guerra US 2010/0125297 and Struhl U.S. Pat. No. 8,162,997) to address the need for minimally invasive approaches. Typically, these mechanisms and techniques involve drilling bone tunnels through the clavicle and subsequently through the coracoid bone, then inserting a suture-based tether between the two bones held by metal buttons on the opposing sides of the bones. These procedures can be technically demanding and are associated with high failure rates (Cook et al., Am J. Sports MEd 2013 41: 142). The lower morbidity seen in percutaneous, endoscopic and arthroscopic surgery makes these techniques very appealing to both patients and physicians. Often, the bone tunnel formation has been associated with bone fractures as well.
One of the primary issues with performing these surgical procedures in a minimally invasive fashion is that of access to the deep-lying bones that are surrounded by soft tissue. Gaining access to the opposing side of the bone in order to place a prosthesis or passing suture is very technically demanding and often not possible. Others, mentioned previously, have attempted to solve this issue by drilling a hole through the most surface-adjacent bone and continuing the drill hole through the deeper lying bone. A suture construct with toggling metal buttons is then passed through the holes in both bones, which tethers the bones together and provides stabilization. While this can be accomplished in a minimally invasive fashion, it can create other, structural issues. The bones may be more susceptible to fracture and if the holes are misaligned, there could be issues with the suture sawing into the bone tunnel.
Passing instruments exist for circumventing bones. A typical instrument for passing a wire or suture under the coracoid or clavicle bones is a generally “C-shaped” hollow needle type or corkscrew type device as described by Whiteside (U.S. Pat. No. 5,501,688). It is often inserted adjacent the bone, then turned axially such that the curved portion is positioned under the bone. A flexible wire is then passed through the lumen to complete the pass. While these types of passers work well for circumventing a bone in the fully open surgical setting, they are very difficult to use in confined space as in a minimally invasive procedure.